The present invention generally relates to the field of pipeline replacement and, more particularly, to an apparatus and method for replacing buried drinking water supply lines made of lead piping which minimizes ground disruption and potential dispersion of the lead during pipe removal.
It is estimated that there are over 6 million installations of lead pipes carrying drinking water from water supply mains to residences in the United States. Due to the harmful effects of lead ingestion by humans and other animals, replacement of this piping is becoming increasingly imperative. In urban areas where space is tight and buried infrastructure is very dense, excavating buried pipelines for replacement is particularly expensive and not always practical or feasible.
Branch water service supply lines are generally less than 2 inches in diameter, with the majority being 1-inch or less. It is common to remove these pipes by accessing and freeing the ends of the pipe, attaching a pulling apparatus to one end, and then pulling the pipe through the ground in which it is buried. Sawing, grinding, and/or fracturing the pipe is not permissible as such operations have the potential to disperse lead particles into the environment. In some instances, replacement pipe will be secured to the end opposite of that being pulled so that the replacement pipe is pulled into position as the old pipe is being removed. Should the pipe being removed break during the pulling process, excavation of the pipe is required which eliminates any advantage of the pull-through replacement method. The risk of breakage when pulling from the leading end or wadding when pulling from the trailing end is greater with lead pipes which are quite malleable and have relatively low tensile strength.
An alternative method involves feeding a cable through the pipe to be removed, securing the cable to the pipe, and then pulling the cable and pipe through the ground. While this approach overcomes limitations in the strength of lead pipe, it does not allow for the lead pipe to be easily separated from the cable during the pulling operation. The result is generally that the pulling cable becomes sacrificial, increasing the costs associated with the replacement operation. One such method is disclosed in U.S. Pat. No. 8,277,147 issued to Cilliers which discloses such a method in which the cable is affixed within the pipe by introduction of a settable fluid which secures the cable to the entire wetted length of the pipe interior.
It would be advantageous to provide a method of replacing buried lead water supply pipe that overcomes these limitations.